Add support for dynamically changing conceallevel between rendered and raw views

# Details

Brought up in #10,
it would be cool if we could conceal links when rendering markdown.

Turns out if conceallevel is set to a high enough value this happens by default.

Hook into this existing feature be increasing conceallevel to 3 when
rendering markdown, and use user default value in all other cases.

Allow individuals to opt out of this by changing the conceallevel
values for both default and rendered.

Author: MeanderingProgrammer

README.md

@@ -7,7 +7,8 @@ Plugin to improve viewing Markdown files in Neovim
 # Features
 
 - Functions entirely inside of Neovim with no external windows
-- Changes between `rendered` view in normal mode and raw view in all other modes
+- Changes between `rendered` view in normal mode and `raw` view in all other modes
+- Changes `conceallevel` between `rendered` and `raw` view based on configuration
 - Supports rendering `markdown` injected into other file types
 - Highlights headings with different groups depending on level and replaces `#`
 - Highlights code blocks and inline code to better stand out
@@ -87,6 +88,13 @@ require('render-markdown').setup({
     bullet = '○',
     -- Character that will replace the > at the start of block quotes
     quote = '┃',
+    -- See :h 'conceallevel' for more information about meaning of values
+    conceal = {
+        -- conceallevel used for buffer when not being rendered, get user setting
+        default = vim.opt.conceallevel:get(),
+        -- conceallevel used for buffer when being rendered
+        rendered = 3,
+    },
     -- Define the highlight groups to use when rendering various components
     highlights = {
         heading = {

demo/demo.gif

@@ -20,7 +20,7 @@ if __name__ == "__main__":
     main()
 ```
 
-- List Item 1
+- List Item 1: with [link](https://example.com)
 * List Item 2: with `inline` code
     * Nested List Item 1
     * Nested List Item 2

demo/sample.md

@@ -19,6 +19,10 @@ local M = {}
 ---@field public latex? string
 ---@field public quote? string
 
+---@class UserConceal
+---@field public default? integer
+---@field public rendered? integer
+
 ---@class UserConfig
 ---@field public markdown_query? string
 ---@field public inline_query? string
@@ -27,6 +31,7 @@ local M = {}
 ---@field public headings? string[]
 ---@field public bullet? string
 ---@field public quote? string
+---@field public conceal? UserConceal
 ---@field public highlights? UserHighlights
 
 ---@param opts UserConfig|nil
@@ -66,6 +71,10 @@ function M.setup(opts)
         headings = { '󰲡 ', '󰲣 ', '󰲥 ', '󰲧 ', '󰲩 ', '󰲫 ' },
         bullet = '○',
         quote = '┃',
+        conceal = {
+            default = vim.opt.conceallevel:get(),
+            rendered = 3,
+        },
         highlights = {
             heading = {
                 backgrounds = { 'DiffAdd', 'DiffChange', 'DiffDelete' },

lua/render-markdown/init.lua

@@ -14,6 +14,10 @@
 ---@field public latex string
 ---@field public quote string
 
+---@class Conceal
+---@field public default integer
+---@field public rendered integer
+
 ---@class Config
 ---@field public markdown_query string
 ---@field public inline_query string
@@ -22,6 +26,7 @@
 ---@field public headings string[]
 ---@field public bullet string
 ---@field public quote string
+---@field public conceal Conceal
 ---@field public highlights Highlights
 
 ---@class State

lua/render-markdown/state.lua

@@ -8,6 +8,7 @@ M.namespace = vim.api.nvim_create_namespace('render-markdown.nvim')
 M.clear = function()
     -- Remove existing highlights / virtual text
     vim.api.nvim_buf_clear_namespace(0, M.namespace, 0, -1)
+    vim.opt_local.conceallevel = state.config.conceal.default
 end
 
 M.refresh = function()
@@ -23,6 +24,7 @@ M.refresh = function()
         return
     end
 
+    vim.opt_local.conceallevel = state.config.conceal.rendered
     vim.treesitter.get_parser():for_each_tree(function(tree, language_tree)
         local language = language_tree:lang()
         if language == 'markdown' then